1. Field of the Invention
The present invention relates generally to inkjet printheads, and more particularly to ink delivery manifolds employed with page wide printheads.
2. Description of the Related Art
Printers, copiers and other related reproduction equipment often employ printheads to deposit ink onto a print medium to provide readable characters. A programmed controller is often utilized to rasterize the data and couple the same to the printhead to cause droplets of ink to be deposited on the print medium in the form of characters, such as letters, symbols, images, etc. Printheads are typically constructed with a number of miniature nozzles that are electrically addressable to cause ink to be jetted from desired nozzles to form the characters on the print medium.
Reproduction equipment utilizing inkjet printheads often use a single printhead that is moved back and forth in a swath laterally across the print medium to deposit ink dots in desired positions along a line. Once each line of ink dots is printed, the print medium is incrementally advanced to print another sequence of ink dots. As a number of lines of ink dots are incrementally printed on the medium, a string of letters or other characters is formed. Each additional string of characters is formed in the same manner, namely alternately moving the printhead in a swath across the print and incrementally advancing the paper.
Another technique for printing characters is to employ a page wide printhead which extends laterally across the print medium. With this technique, the page wide printhead does not move, but rather prints a single line of ink dots substantially simultaneously. Then, the print medium is advanced so that a subsequent line of ink dots can be printed. As can be appreciated, the use of the page wide printhead significantly reduces the time required to print a string or page of characters.
While the utilization of a page wide printhead is an efficient method for quickly printing many characters, the construction of such type of printheads is more complicated and thus more costly and prone to manufacturing errors. Many of the components of a printhead are constructed using semiconductor wafers and corresponding processing techniques. As such, the fabrication of a page wide printhead for standard letter-size paper, requires a printhead having a length approximately equal to the width of the target print media. In this instance, the conventional practice is to use a number of individual printheads that are mounted on a support that spans the width of the print medium. The printheads are staggered or offset so that a standard space exists between the last nozzle of one printhead and the first nozzle of the adjacent printhead.
In addition to printheads, a manifold is often used to couple the liquid ink from a reservoir to the various nozzles of the individual printheads. The manifold construction is more complicated when it is desired to print characters in color. If, for example, magenta, yellow, cyan and black ink colors are utilized for the primary colors to print an image of any color, then the manifold must have at least four different channels to accommodate the four different colors of ink. Moreover, the different ink channels must be extended to the various nozzle structures of the individual printheads. It can thus be appreciated that the construction of the ink manifold is complicated, in that very small channels must be formed in circuitous paths in the manifold to couple the liquid ink to the individual nozzle structures. Owing to the fact that the individual printheads can each have thousands of nozzles, the ink delivery manifold can be challenging to manufacture.
Because of its complexity, a manifold for routing liquid ink from a source to the printhead nozzles is often constructed of a semiconductor material which can be processed with micron-size features. The manifold can be made in two halves, each etched to form the desired features, such as the many ink channels, and then bonded together so that the ink channels are closed, except at the input end, and the output ends which are mated to the printhead nozzles. However, even when manufacturing manifolds for page wide printheads, the semiconductor material often needs to be as long as the print medium is wide. In other words, the semiconductor manifold can be made eight and one-half inches long for printing on a letter-size page. This may require a ten-inch diameter semiconductor wafer to make several ink delivery manifolds. While this is possible, this technique is wasteful of wafer area, and thus makes the one-piece semiconductor manifold not only costly, but also fragile and prone to breakage.
From the foregoing, it can thus be seen that a need exists for a technique to make a semiconductor manifold for an ink jet printhead that is cost effective and better adapted for page wide applications. Another need exists for a technique for fabricating a tiled ink manifold that better utilizes the area of a semiconductor wafer, and facilitates assembly of the printhead components.